Sunday, July 22, 2007

sweetening exyus

i did more work this week to sweeten the exyus framework.

304 fixed

first, i fixed my broken 304 handling. when i was storing all cached data on disk, the 304 handler would compare the file timestamps against the if-modified-since and etag headers (serialized) to determine if 304 was the proper response. when i moved the cache into memory, my 304 checking was broken. i would return data from the cache, but always return false for 304 checking (no file data anymore!). to fix this, i resurrected a simple cache object that has timestamp, etag, and payload properties. now all resource entries in the memory cache are cache objects and my 304 checking is working again. sweet!

support for HTTP HEAD

second, i added support for the HTTP HEAD method. actually, it was embarrassingly easy. i just call the GET method and then toss out the response content. this allows for all the usual good stuff (304 checking, marking the item w/ last-modified, and etag, etc.), but doesn't return a body. now i have solid HEAD support!

cache invalidation implemented

my other big task was to implement a simple cache invalidation pattern. i did thsi by implementing support for the cache-control:no-cache header in my GET requests. that means anyone can issue a GET request to a URI with the cache-control:no-cache header and that will force the system to invalidate any existing cached version of that resource and return a fresh one. of course, along the way, this fresh version will get placed in the cache for future calls! *and* (to make it all really nice), you can even use HEAD instead of GET!

simplify data object declaration

finally, i tightened up the initial declaration for data object. no longer do you need to declare each verb XSD/XLST set. you just supply a single directory location that holds the [verb].xsd and/or [verb].xsl files. this emphasizes the standard interface concept for HTTP/REST and simplifies/shortens the declaration code. now, a data object declaration looks like this:

public class websiteData : SqlXmlHandler
public websiteData()
this.ConnectionString = "mamund_personal_db";
this.UrlPattern = @"/websites/(.*).xcs\??(.*)$";
this.DocumentsFolder = "~/documents/websites/";
this.XHtmlNodes = new string[] { "//description" };
this.ClearCacheUri = new string[]
{ "/blogging/",

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